ATF Drain & Fills: Does interim mileage matter?

[Mustang_Cougar]

I'm doing a series (3) of drain & fills on my Ranger (4R44E, 106K miles) as opposed to a complete transmission flush. The first one involved a new filter, installing a drain plug & 4qts of ATF. Anyway, this truck is hardly ever driven and, after two months & only 30 city/highway miles, I went ahead and did the second drain & fill. The drained ATF was obviously lighter and definitely had a more pungent "fresh ATF" smell (geeze, that sounds lame); though it's not pink/reddish like new fluid, I was pretty happy to see that the old & new ATF mixed so well in such a short mileage interval.

So, is an arbitrary mileage interval of 1K or 5K really optimal? Or does the simple act of engaging all the A/T gears in a short time (like my 30 miles) effectively mix the ATF as much as it ever will?

Thanks for any insights/opinions!

 

[hate2work]

You have a pump in your transmission that pumps the entire volume in about 1 minute, so it doesn't take long to mix well. The reason people pick an arbitrary number like 1k or 5k is so that they can remember when to do it next as a scheduled maintenance item. But if you're trying to get 3 drain and refills done over the weekend, just driving a few miles mixes it plenty.

 

[Mustang_Cougar]

Thanks H2W.

 

[Eddie]

Since the fluid does not circulate through the hydraulic valves quickly, I would drive many shift cycles between changes to get the maximum benefit. I'd suggest a 10+ mile run in some traffic to get the AT to shift through the gears often. JMO. Ed

 

[crinkles]

i just did two drain and fills 5,000 miles apart at 45,000 miles.

less time to spend on your back.

i would drive at least a week, maybe there are some chemistry things going on.